Heretofore, a flow rate control valve and assembly method therefor have been known, in which the flow rate control valve is connected via piping to a fluid pressure apparatus such as a cylinder or the like, and which is capable of controlling operations of the fluid pressure apparatus by adjusting the flow rate of a fluid that is supplied to and discharged from the fluid pressure apparatus.
With such a flow rate control valve, for example, as disclosed in Japanese Laid-Open Patent Publication No. 2001-141090, in a center portion of a body which is formed in a tubular shape, a tubular shaped valve main body is installed perpendicularly with respect to a longitudinal direction of the body. A throttling valve for adjusting the flow rate of a fluid that flows through the interior of the body is screw-engaged so as to be capable of advancing and retracting in an insertion hole of the valve main body. A lower end side of the throttling valve which faces the body is formed in a gradually tapered shape. Further, on the lower end of the valve main body, a check valve is disposed on an outer peripheral surface thereof, which abuts against a guide wall formed in the fluid passage inside the body, and multiple holes that communicate between exterior and interior regions of the valve main body open into the center portion along the axial direction of the valve main body.
Additionally, by rotating the throttling valve and effecting advancing and retracting movements thereof, the size of a gap formed between a lower end portion of the throttling valve and the valve main body is changed, such that a fluid supplied from one of the fluid passages flows to the other fluid passage, while the flow rate of the fluid is controlled by flowing through the interior of the valve main body, through the hole and passing through the gap. By controlling the flow rate of the fluid so as to obtain a desired flow rate, operations of the fluid pressure apparatus connected to the fluid control valve are controlled.
However, in the aforementioned conventional technique, for example, when the valve main body is manufactured, after the outer shape thereof is formed by a cutting process, the multiple holes therein are formed in yet another process step. Therefore, the manufacturing steps (process steps) are greater in number and complex. Further, recently, there has been a demand to decrease the manufacturing cost required for fluid control valves, as well as to improve productivity and the ease with which fluid control valves can be manufactured.